FIG. 1 is a schematic 100 showing a semiconductor package. An example of a semiconductor package is a Power Quad-Flat-Nonleaded (QFN) package or a power Dual-Flat-Nonleaded (DFN) package. A semiconductor package may include a chip 102 mounted on a substrate or carrier such as a leadframe 104. The chip 102 and the carrier 104 may be at least be partially covered by an encapsulant material 106. The thermal resistance of a junction (J) at an ambient (A) temperature, RthJA, of semiconductor packages depend on the cooling performance of the packages. For instance, an application level Power DFN package such as PG-TDSON-8 (Plastic Green Thin Dual Small Outline Non-leaded Package), also known as SuperSO8 or S3O8, may strongly depend on cooling performance.
FR (flame retardant)-4 (or FR4) is a grade designation assigned to glass-reinforced epoxy laminate sheets, tubes, rods and printed circuit boards. For many semiconductor packages using FR4 substrates, the cooling performance is not ideal. The non-ideal cooling performance limits the thermal resistance of the semiconductor packages.